Various items, such as gas turbine engine components, can be manufactured by joining individually fabricated segments together to form a single, unitary component. Cracks or other damage in such components may also be repaired. Diffusion bonding, which involves the solid-state movement of atoms and grain growth across a joint interface, has been used to join and/or repair such components. Diffusion bonding allows for the fabrication and repair of complex assemblies having bonded areas that are practically indistinguishable from the adjacent segment materials, even under close metallurgical examination. These bonds comprise microstructures and mechanical properties that are substantially similar to those of the segments being joined together. However, diffusion bonding requires high pressures, which can cause distortion of the components.
Transient liquid phase bonding is a hybrid brazing and diffusion bonding process that overcomes the presence of weaker filler material typically associated with braze joints by also utilizing diffusion bonding. In transient liquid phase bonding, one or more interlayer materials are disposed between two or more segments being joined together to form an assembly. When the assembly is heated to the bonding temperature, the interlayer materials melt, filling in the gaps between the segments. While the assembly is held at the bonding temperature, interdiffusion of certain alloying elements occurs between the interlayer and the adjacent segments, causing a compositional change at the joint, which isothermally solidifies the joint and creates an initial bond between the segments. Holding the assembly at the bonding temperature for a longer period of time allows a substantially homogenous diffusion bond to form between the segments. Transient liquid phase bonding requires very low pressures, and therefore does not cause distortion of the components. This makes transient liquid phase bonding an attractive assembly and/or repair method.
Current transient liquid phase bonding systems and methods do not produce sufficiently strong bonds between substrates for some applications. Therefore, it would be desirable to be able to produce stronger bonds when utilizing transient liquid phase bonding techniques. It would also be desirable to improve the hardness, microstructure, and/or homogeneity (chemical and/or microstructural) of such bonds. It would be further desirable to be able to join dissimilar materials by utilizing such techniques.